Primary hepatic carcinoid tumor presenting as Cushing's syndrome.

Hepatic carcinoid tumors are very uncommon; most are clinically non-functional and very few present with the symptoms of carcinoid syndrome. ACTH-producing carcinoid tumors most commonly originate in the lung or thymus and present insidiously with bronchospasm and/or chest mass. Occasionally, ectopic ACTH syndromes have been reported in association with pancreatic islet cell tumors, medullary thyroid cancer, pheochromocytoma, small-cell lung carcinoma, and rarely, ovarian and prostate tumors. We report here a patient with an ectopic ACTH-secreting primary hepatic carcinoid tumor who presented with cushingoid appearance, profound proximal muscle weakness, severe lower extremity edema, and markedly elevated urinary free cortisol. ACTH levels were in the low normal range. A solitary vascular hepatic lesion was found on magnetic resonance imaging, which was isodense with the surrounding liver on octreotide scan and photopenic on an 18-fluorodeoxyglucose (18FDG)-positron emission tomography (PET) scan. Following surgical resection of the hepatic tumor, histopathology confirmed an ACTH-secreting neuroendocrine tumor (NET), the patient had complete resolution of hypercortisolemic symptoms and remains in remission, now 4 yr after hepatic tumor resection. This case reports the first ACTH-secreting primary hepatic NET presenting as ectopic Cushing's syndrome. Interesting aspects of this case include the presence of a pituitary incidentaloma, the low normal ACTH, and photopenia on 18FDG-PET imaging.

Serum cortisol levels in Cushing's syndrome after low- and high-dose dexamethasone suppression.

To standardize the cutoff points of serum cortisol values in the evaluation of Cushing's syndrome during a low- and high-dose dexamethasone suppression test, daily serum cortisol measurements (0800 hours and 1600 hours) and urinary 17-hydroxycorticosteroids were compared (Study A). Forty-seven subjects were studied (11 normal subjects, 15 patients with Cushing's disease, five patients with adrenal adenoma, and 16 subjects with suspected Cushing's syndrome). A serum cortisol measurement at 1600 hours of more than 5 micrograms/dL on low-dose dexamethasone suppression and more than 10 micrograms/dL on high-dose dexamethasone were ascertained to be nonsuppressed values. A baseline dehydroepiandrosterone-sulfate value less than 0.4 microgram/mL indicated patients with an adrenocorticol adenoma. Study B was a prospective study of 17 patients in which no urine samples were collected. Serum cortisol levels, obtained in 1600 hours on the second day of low- and high-dose dexamethasone, accurately allowed a differential diagnosis of suspected Cushing's syndrome. Serum cortisol measurements can replace the urinary 17-hydroxycorticoid measurements in a cost-effective manner without a decrease in the degree of accuracy.